ExportCSV

protected void btnExport_Click(object sender, EventArgs e)
  {
      ExportCSV(CreateData(),"Test")
  }

  public void ExportCSV(DataTable data, string fileName)
  {

    HttpContext context = HttpContext.Current;

    context.Response.Clear();
    context.Response.ContentType = "text/csv";
    context.Response.AddHeader("Content-Disposition", "attachment; filename=" + fileName + ".csv");

    //rite column header names
    for (int i = 0; i < data.Columns.Count - 1; i++)
    {
      if (i > 0)
      {
        context.Response.Write(",");
      }
      context.Response.Write(data.Columns[i].ColumnName);
    }
    context.Response.Write(Environment.NewLine);

    //Write data
    foreach (DataRow row in data.Rows)
    {

      for (int i = 0; i < data.Columns.Count - 1; i++)
      {
        if (i > 0)
        {
          context.Response.Write(",");
        }
        context.Response.Write(data.Columns[i].ColumnName);
      }
      context.Response.Write(Environment.NewLine);
    }
    context.Response.End();

  }

  private DataTable CreateData()
  {

    DataTable table1;
    table1 = new DataTable("Customers");

    DataRow row1, row2, row3;

    DataColumn colName = new DataColumn("CustomerName", System.Type.GetType("System.String"));
    DataColumn colCity = new DataColumn("City", System.Type.GetType("System.String"));
    table1.Columns.Add(colName);
    table1.Columns.Add(colCity);

    row1 = table1.NewRow();
    row1["CustomerName"] = "Microsoft";
    row1["City"] = "Redmond";
    table1.Rows.Add(row1);

    row2 = table1.NewRow();
    row2["CustomerName"] = "Amazon.com";
    row2["City"] = "Seattle";
    table1.Rows.Add(row2);

    row3 = table1.NewRow();
    row3["CustomerName"] = "IBM";
    row3["City"] = "Armonk";
    table1.Rows.Add(row3);

    return table1;

  }

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